Interlocking Fence System and Method

ABSTRACT

An interlocking fence system is disclosed. Two spaced-apart upright posts ( 8, 10 ) attached to a grade G support an upper rail ( 4 ) with an offset locking aperture ( 26 ) and an alignment aperture ( 32 ) and further support a lower rail ( 6 ) with an alignment aperture ( 40 ). A picket ( 2 ) has a locking slot ( 22 ) with an edge ( 28 ) of the locking aperture ( 26 ) in the upper rail ( 4 ) serving as a tab to restrict axial movement when inserted therein. Alignment aperture ( 32 ) in the upper rail ( 4 ) and alignment aperture ( 40 ) in the lower rail ( 6 ) serve to restrict lateral movement of the picket ( 2 ). To support the rails ( 4, 6 ), retaining slots ( 24, 24′ ) in the upper rail ( 4 ) and retaining slots ( 42, 42′ ) in the lower rail ( 6 ) can be retained by an edge ( 38, 50, 38′, 50′ ) in support apertures ( 12, 14, 16, 18 ) in the posts ( 8 A,  10 A).

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. Ser. No. 11/277,316, filed Mar. 23, 2006, now U.S. Pat. No. ______.

BACKGROUND

This invention relates to fencing, more particularly, to an interlocking fence system that can allow construction of a complete fence without welding or the use of screws, bolts, nails, rivets, pins, clips, brackets, rods, or other fasteners.

Building a fence, for example an ornamental iron fence, typically involves assembling panels of two major types. One type is a pre-welded panel where the horizontal rails are welded to the pickets and then attached to the posts by welding or by the use of a fastener. The other type of panel requires the rails and pickets to be assembled with a usually complicated system of screws, bolts, nails, rivets, pins, clips, brackets, or rods.

Most fence systems in use today do not appear the same from both sides. For example, a welded fence panel typically has the pickets welded to one side of the rails. This produces an inside and an outside view of the fence panel that differ. Similarly, with a fence panel that uses screws to fasten the pickets to the rails, the screw heads are typically visible on one side only.

Constructing a welded fence requires skilled welding labor and welding equipment at the jobsite. The skill and equipment necessary to weld a fence is in many cases beyond the do-it-yourself person. However in some areas high shipping costs can preclude shipping pre-welded panels.

In response, fence panels have been developed that require no welding and are completely assembled in the field. These designs can be shipped more economically by carriers that cannot carry a large panel assembly. However, these fencing kits typically require the use of screws, nails, rivets, pins, clips, brackets, or rods to assemble the rails and the pickets. On the jobsite these various fastening methods require an installer to assemble an array of components, for example, by drilling holes and installing screws, bolts, or clips to retain the pickets and/or rails in place. Lost or non-included fasteners, especially specialized fasteners, must be ordered and can delay the installation. Fasteners can be installed incorrectly and installation can require specialized tools for the specific fence system. Further, the more parts required for the fence system, the higher the cost, not only in manufacturing, but assembly as well. Panels that are assembled in the field by welding are also available however, welded panels must be rust-proofed (e.g., painted) in the field to repair the weld area. Typically, the more jobsite welding, the more difficult it becomes to maintain quality control.

There is a need for a simple fence system for a do-it-yourself individual or even a contractor that allows for shorter installation times, less training, and more efficient transportation, as well as lower cost and ease of manufacture.

SUMMARY OF THE INVENTION

The present invention is directed to an interlocking fence system and a method of assembling the same. By employing pickets that interlock with the rails, the use of fasteners or other attachment hardware can be minimized or even avoided altogether. Assembly is simplified, and the pickets, rails, posts and other component parts can be easily transported to the installation site. The interlocking system is ideal for the do-it-yourselfer and contractor.

In one embodiment, the interlocking fence system can include first and second spaced-apart upright posts attached to a grade. A locking rail and an alignment rail extend between the first and second posts. The system includes a picket with a transverse profile and a locking slot extending inwardly from a side surface thereof. A plurality of alignment apertures are provided in the rails comprising at least one alignment aperture in the alignment rail and a locking aperture formed in the locking rail. The alignment apertures have a profile matching the transverse profile of the picket to receive the picket and are in upright alignment to restrict lateral movement of the picket. The locking aperture has a profile to receive the picket at an angle offset from an axis of the alignment apertures. A lateral offset of the locking aperture from the alignment apertures defines a tab for insertion to the locking slot when the picket is aligned by the alignment apertures. A depth of the locking slot can be at least equal to the lateral offset of the locking aperture.

In an embodiment, the fence system can include a stop disposed in the support aperture on a side of the locking rail opposite the retaining slot.

In another embodiment, the locking rail can be tubular and the locking aperture can be formed in an upper surface thereof. At least one alignment aperture can be formed in a lower surface of the locking rail.

In yet another embodiment, the alignment rail can be a U-channel with at least one alignment aperture.

In another embodiment, the alignment rail can be tubular with at least one alignment aperture formed in an upper surface thereof, and optionally another in a lower surface thereof.

In yet another embodiment, the interlocking fence system can include a plurality of the pickets, each with a corresponding locking aperture and plurality of alignment apertures formed in the rails to receive the picket.

In another embodiment, the interlocking fence system can further comprise an inwardly extending retaining slot formed in a side surface adjacent one or both ends of the locking rail to receive a respective edge of a support aperture in a respective post.

In an embodiment, the fence system can include a stop inserted in the support aperture on a side of the locking rail opposite the retaining slot to inhibit release of the edges of the support apertures from the retaining slots. Alternatively or additionally, the fence system can include an end stop inserted in at least one of the posts adjacent the end of the respective locking rail to inhibit axial movement of the locking rail. In one embodiment, the end stop comprises a successive locking rail engaged in a successive support aperture opposite the respective first or second support aperture.

In yet another embodiment, the interlocking fence system can include an inwardly extending retaining slot formed in a side surface adjacent one or both ends of the alignment rail to receive a respective edge of a support aperture in a respective post.

In an embodiment, the fence system can include a stop inserted in the locking aperture on a side of the locking rail opposite the locking slot to inhibit release of the edges of the locking apertures from the locking slots. Alternatively or additionally, the fence system can include an end stop inserted in at least one of the posts adjacent the end of the respective alignment rail to inhibit axial movement of the alignment rail. In one embodiment, the end stop comprises a successive alignment rail engaged in a successive support aperture opposite the respective first or second support aperture. In one embodiment, the posts are tubular and the method includes filling the posts adjacent the support apertures with a hardenable filler such as cement, for example.

In another embodiment, a method of assembling the interlocking fence system can include the following steps: (a) inserting the picket through the locking aperture and a first one of the alignment apertures in the locking rail at an offset angle to position the locking slot adjacent the tab, (b) pivoting the picket about the first alignment aperture from the offset angle to an alignment angle to engage the tab into the locking slot, (c) and inserting the picket through a second one of the alignment apertures in the alignment rail.

In another embodiment, the method can further include installing first and second upright, laterally spaced posts in a grade, securing opposite ends of the locking rail to the posts, and securing opposite ends of the alignment rail to the posts, wherein the alignment rail is vertically spaced from the locking rail. In one embodiment, the locking rail is secured to the posts before the alignment rail, for example, the locking rail is secured to the posts in advance of step (c), preferably in advance of step (a), and the alignment rail is secured to the posts after step (c).

Securing the opposite ends of the locking rail can include disposing one of the ends of the locking rail into a support aperture in one of the posts to position a retaining slot formed in the rail adjacent an edge of the support aperture, and moving the locking rail transversely, preferably downwardly, to engage the edge in the retaining slot. In one embodiment, the locking rail has a said retaining slot formed adjacent both ends, preferably at an equal distance from each end, and a spacing between the retaining slots corresponds to a spacing between support apertures formed in the first and second posts.

In an embodiment, the support aperture in the first post has a depth that is at least equal to the sum of the respective distances from the ends of the locking rail to the respective retaining slots, and the method includes the following steps: (1) inserting a first end of the locking rail into the first support aperture while the second end is positioned laterally to one side of the second post, preferably adjacent the second support aperture, to provide clearance between the second end of the locking rail and the second post; (2) laterally pivoting the second end of the locking rail into alignment with the second support aperture in the second post; (3) moving the locking rail axially to position the first and second retaining slots adjacent respective edges of the first and second support apertures; and (4) moving the locking rail laterally, preferably downwardly, to engage the respective edges of the first and second support apertures in the first and second retaining slots.

The method can also include inserting stops into the first and second support apertures on a side of the locking rail opposite the respective first and second retaining slots to inhibit release of the edges of the support apertures from the retaining slots. Alternatively or additionally, the method can include inserting an end stop in at least one of the posts adjacent the end of the respective locking rail to inhibit axial movement of the locking rail. In one embodiment, the end stop comprises a successive locking rail engaged in a successive support aperture opposite the respective first or second support aperture. In another embodiment, the posts are tubular and the method includes filling the posts adjacent the support apertures with a hardenable filler such as cement, for example.

Securing the opposite ends of the alignment rail can include disposing one of the ends of the alignment rail into a support aperture in one of the posts to position a retaining slot formed in the rail adjacent an edge of the support aperture, and moving the alignment rail transversely, preferably downwardly, to engage the edge in the retaining slot. In one embodiment, the alignment rail has a said retaining slot formed adjacent both ends, preferably at an equal distance from each end, and a spacing between the retaining slots corresponds to a spacing between support apertures formed in the first and second posts.

In an embodiment, the support aperture in the first post has a depth that is at least equal to the sum of the respective distances from the ends of the alignment rail to the respective retaining slots, and the method includes the following steps: (1) inserting a first end of the alignment rail into the first support aperture while the second end is positioned laterally to one side of the second post, preferably adjacent the second support aperture, to provide clearance between the second end of the alignment rail and the second post; (2) laterally pivoting the second end of the alignment rail into alignment with the second support aperture in the second post; (3) moving the alignment rail axially to position the first and second retaining slots adjacent respective edges of the first and second support apertures; and (4) moving the alignment rail laterally, preferably downwardly, to engage the respective edges of the first and second support apertures in the first and second retaining slots.

The method can also include inserting stops into the first and second support apertures on a side of the alignment rail opposite the respective first and second retaining slots to inhibit release of the edges of the support apertures from the retaining slots. Alternatively or additionally, the method can include inserting an end stop in at least one of the posts adjacent the end of the respective alignment rail to inhibit axial movement of the alignment rail. In one embodiment, the end stop comprises a successive alignment rail engaged in a successive support aperture opposite the respective first or second support aperture.

In another aspect, the present invention provides a method of assembling an interlocking fence system comprising the steps of: (a) providing an interlocking fence system comprising: (1) upper and lower rails each including a like plurality of spaced apart alignment apertures, wherein at least one of the upper and lower rails is tubular wherein the respective alignment apertures are formed in one of an upper and a lower surface thereof and a like plurality of spaced apart locking apertures is formed in the other one of the upper and lower surfaces, and (2) a plurality of pickets with a transverse profile and a locking slot extending inwardly from a side surface thereof for receiving a tab defined by an edge of the locking aperture; (b) inserting a respective one of the pickets through each of the locking and alignment apertures in the tubular rail and a first one of the alignment apertures in the tubular rail at an offset angle to position the locking slot adjacent the tab; (c) pivoting the pickets from the offset angle to an alignment angle to engage the tab into the locking slot, and (d) inserting each of the pickets through a second one of the alignment apertures and coaxially aligning the alignment apertures.

In an embodiment, the method just mentioned can also include: installing first and second upright, laterally spaced posts in a grade; securing opposite ends of the at least one tubular rail to the posts; and securing opposite ends of the other of the upper and lower rails to the posts, wherein the upper and lower rails are vertically spaced from each other. The tubular rail in an embodiment can be secured to the posts before the other of the upper and lower rails. In an embodiment, the steps of securing the opposite ends of the rails can include: disposing one of the ends of the respective rail into a support aperture in one of the posts to position a retaining slot formed in the respective rail adjacent an edge of the support aperture; and moving the respective rail transversely to engage the edge in the retaining slot.

In another embodiment, the steps of securing the opposite ends of the rails can include the steps of: (1) inserting a first end of the respective rail into a first support aperture in the first post while a second end is positioned laterally to one side of the second post adjacent a second support aperture to provide clearance between the second end of the respective rail and the second post; (2) laterally pivoting the second end of the respective rail into alignment with the second support aperture in the second post; (3) moving the respective rail axially to position a first and a second retaining slot adjacent a respective edge of the first and second support apertures; and (4) moving the respective rail laterally to engage the respective edges of the first and second support apertures in the first and second retaining slots. In an embodiment, the method can also include inserting at least one stop into each of the first and second support apertures on a side of the respective rail opposite the respective first and second retaining slots to inhibit release of the edges of the support apertures from the retaining slots.

In another embodiment the method can additionally or alternatively include inserting an end stop in at least one of the posts adjacent the end of the respective locking and alignment rails to inhibit axial movement of the respective locking and alignment rails.

In another embodiment, this method can include providing tubular posts, and filling the posts adjacent the support aperture with a hardenable filler.

A further aspect of the invention provides an interlocking fence system including first and second spaced-apart upright posts attached to a grade, and upper and lower rails extending between the first and second posts, wherein at least one of the upper and lower rails is tubular. The system can include a picket with a transverse profile and a locking slot extending inwardly from a side surface thereof. The picket can pass through the rails at a locking aperture and can then be pivoted into alignment with an axis of a plurality of spaced apart, coaxial alignment apertures. The plurality of alignment apertures in the rails can include-at least one alignment aperture in each of the upper and lower rails, wherein the alignment aperture in the at least one tubular rail is in one of an upper and a lower surface thereof and the locking aperture is in the other one of the upper and lower surfaces. The alignment apertures can have a profile matching the transverse profile of the picket and be in upright alignment with respect to an axis of the picket to restrict lateral movement of the picket. The locking aperture can have a profile matching the transverse profile of the picket to receive the picket at an angle offset from an axis of the alignment apertures for assembly, wherein the locking aperture is offset laterally with respect to the axis of the picket, and wherein the lateral offset of the locking aperture defines a tab inserted into the locking slot with the picket aligned by the alignment apertures.

In one embodiment of the interlocking fence system just described, the locking aperture can be formed in the upper or lower surface of the tubular rail. Either or both of the upper and lower rails can be tubular.

In an embodiment, the system can include a plurality of said pickets, each with a corresponding locking aperture and plurality of alignment apertures formed in the rails receiving the picket. A depth of the locking slot can be at least equal to the lateral offset of the locking aperture. In an embodiment, the system can include inwardly extending retaining slots formed in a side surface adjacent an end of the upper and lower rails to receive a respective edge of a support aperture in a respective post.

A further aspect of the system provides a method of assembling an interlocking fence system comprising the following steps: (a) providing an interlocking fence system comprising: (1) a plurality of vertically spaced tubular rails including at least an upper rail and a lower rail, each rail including a like plurality of spaced apart alignment apertures formed in an upper surface of the rails, and a like plurality of locking apertures formed in a lower surface of the rails, wherein each of the alignment apertures is laterally offset from a respective locking aperture to define a locking tab at an edge of the locking aperture, wherein a picket retention corridor is defined by each set of corresponding alignment and locking apertures among the plurality of rails, and (2) a plurality of pickets having locking slots extending inwardly from a side surface thereof for receiving the tabs from the locking apertures in a profile for retention in the picket retention corridor; (b) inserting one of the plurality of the pickets through each of the corresponding locking and alignment apertures of the upper rail in a respective picket retention corridor at a first offset angle to position the corresponding locking slot adjacent the tab; (c) pivoting the pickets inserted in step (b) from the first offset angle toward an alignment angle to engage the tab into the corresponding locking slot and lock the picket s in the upper rail, and (d) inserting one of the locked pickets from step (c) through each of the corresponding locking and alignment apertures of the lower rail in a respective picket retention corridor at a second offset angle to position the corresponding locking slot adjacent the tab in the lower rail; and (e) pivoting the pickets inserted in step (d) from the second offset angle toward an alignment angle to engage the tab into the corresponding locking slot and lock the pickets in the lower rail and to coaxially align the alignment apertures in each picket retention corridor.

In another embodiment, the method can include installing first and second upright, laterally spaced posts in a grade, and securing opposite ends of the upper and lower rails to the posts. The step of securing the opposite ends of the rails can include in one embodiment, disposing one of the ends of the respective rail into a support aperture in one of the posts to position a retaining slot formed in the respective rail adjacent an edge of the support aperture; and moving the respective rail transversely to engage the edge in the retaining slot.

Alternatively or additionally, the step of securing the opposite ends of the rails can include: (1) inserting a first end of the respective rail into a first support aperture in the first post while a second end is positioned laterally to one side of the second post adjacent a second support aperture to provide clearance between the second end of the respective rail and the second post; (2) laterally pivoting the second end of the respective rail into alignment with the second support aperture in the second post; (3) moving the respective rail axially to position a first and a second retaining slot adjacent a respective edge of the first and second support apertures; and (4) moving the respective rail laterally to engage the respective edges of the first and second support apertures in the first and second retaining slots.

In another embodiment, the method can include providing tubular posts and filling the posts adjacent the support aperture with a hardenable filler.

A still further aspect of the invention is an interlocking fence system including first and second spaced-apart upright posts attached to a grade, upper and lower tubular rails extending between the first and second posts, and a picket with a transverse profile and upper and lower locking slots extending inwardly from a side surface thereof. The picket can pass through each of the rails at a respective locking aperture and then be pivoted into alignment with an axis of respective alignment apertures in each of the upper and lower rails. The locking apertures can be laterally offset from the respective alignment apertures to define a locking tab received in the locking slot of the picket. In an embodiment, the alignment apertures can be formed in upper surfaces of the rails and the locking apertures in lower surfaces of the rails. The system can include a plurality of said pickets. In one embodiment, the lateral offset of the locking apertures from the alignment apertures in the upper rail is greater than the lateral offset of the locking apertures from the alignment apertures in the lower rail and in another embodiment, the lateral offset of the locking apertures from the alignment apertures in the upper rail is from about 1.5 to about 2.5 times, for example, twice as great as, the lateral offset of the locking apertures from the alignment apertures in the lower rail.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a section of an assembled interlocking fence system, according to one embodiment of the invention.

FIG. 2 is a perspective view of a picket with a locking slot, according to one embodiment of the invention.

FIG. 3 is a cross-sectional view of the circled portion of the interlocking fence system of FIG. 1, as marked with a 3.

FIG. 4 is a perspective view of a locking rail, according to one embodiment of the invention.

FIG. 5 is a perspective view of an alignment rail, according to one embodiment of the invention.

FIG. 6 is a partial cross-sectional and partial perspective view of a picket inserted into locking rail, according to one embodiment of the invention.

FIG. 7 is a schematic view of a picket connected to the locking aperture of the locking rail and an alignment rail being disposed towards the picket, according to one embodiment of the invention.

FIG. 8 is a schematic view of a picket installed in a locking and an alignment rail, according to one embodiment of the invention.

FIG. 9A is a cross-sectional schematic view of the ends of a locking rail and an alignment rail, supporting a plurality of interlocked pickets, disposed into respective support apertures in a first post, according to one embodiment of the invention.

FIG. 9B is a cross-sectional schematic view of the interlocking fence system of FIG. 9A wherein the opposing ends of the locking rail and the alignment rail have been inserted into respective support apertures in the second post and the rails are supported by a retaining slot therein resting on an edge of each support aperture.

FIG. 10 is a perspective view of a picket, according to a second embodiment of the invention.

FIG. 11 is a schematic view of two adjacent pickets installed in a locking rail and an alignment rail, according to a second embodiment of the invention.

FIG. 12 is a top perspective view of the locking rail of FIG. 11, illustrating zigzag mounting pattern and the lateral offset of each set of a locking aperture and an alignment aperture.

FIG. 13 is a perspective view of a picket with upper and lower locking slots, according to an alternative embodiment of the invention.

FIG. 14 is a cross-sectional view of the double-locking picket of FIG. 13 used in an interlocking fence system according to an embodiment of the invention.

FIG. 15 is a partial cross-sectional and partial perspective assembly schematic wherein one of the double locking pickets of FIG. 13 is shown with the upper end inserted into the upper locking rail, according to an embodiment of the invention.

FIG. 16 is a schematic view of the double-locking picket system of FIGS. 13-15 during assembly wherein, following engagement of each of the pickets in the upper locking rail, the lower ends of the pickets are partially inserted into the upper aperture of the lower rail, according to an embodiment of the invention.

FIG. 17 is an assembly schematic view following FIG. 16 wherein the lower rail is moved longitudinally to pivot and slide the lower end of the picket into the bottom locking aperture in the lower rail while maintaining the upper end of the picket in engagement with the upper rail, according to an embodiment of the invention.

FIG. 18 is an assembly schematic following FIG. 17 wherein the lower rail is moved longitudinally to pivot the pickets so that each lower locking slot is engaged in the respective lower picket and the pickets are aligned in the alignment apertures in the upper and lower rails, according to an embodiment of the invention.

FIG. 19 illustrates an alternative embodiment of the interlocking fence system according to the invention wherein transverse support pins are used to help support the pickets on the lower rail.

FIG. 20 is a plan section of the lower rail in the fence system of FIG. 19 as seen along the lines 20-20.

DETAILED DESCRIPTION

With reference to the figures wherein like reference numerals are used to refer to like parts, FIG. 1 shows a section of an interlocking fence system 1. Two spaced-apart upright posts (8, 10) are attached at grade G by cement 20, however any mooring means can be used. A locking rail 4 and an alignment rail 6 extend between the posts (8, 10). The rails (4, 6) can attach to the posts (8, 20 10) through any means known the art. The rails (4, 6) are both illustrated as being retained in support apertures (12,14; 12′,14′ in first post 8) (16,18; 16′,18′ in second post 10).

FIG. 2 illustrates a picket 2, with a locking slot 22 extending inwardly from a side surface of the picket 2. The picket 2, posts (8, 10), and rails (4, 6) can be solid in cross-section or tubular and/or U-shaped as illustrated, and the forming of slots is known by one of ordinary skill in the art. Further, an ornamental cap or any other ornamental accoutrement (not shown) can be added to the picket 2 without departing from the spirit of the invention.

FIG. 3 is a cross-sectional view of circled area 3 in FIG. 1. Locking rail 4 is shown engaged with a picket 2. Locking rail 4 has a locking aperture 26 formed in an upper surface thereof. Edge 28 of the locking aperture 26 in locking rail 4 serves as a tab to restrict axial movement by insertion into the locking slot 22 on the picket 2. The picket 2 is also disposed through alignment aperture 32 formed in the lower surface of the locking rail 4. Edge 36 of alignment aperture 32 provides a profile matching that of the picket 2 to restrict the lateral movement of the picket 2. The interaction of the picket 2 and the alignment rail 6 (FIG. 1) is discussed below in reference to FIGS. 7-8.

Locking rail 4 is supported by the support aperture 12 formed in post 8. Edge 38 of support aperture 12 thus forms a tab to insert into the inwardly extending retaining slot 24 formed in the locking rail 4. Referring again to FIG. 1, a respective retaining slot (24′ in FIG. 7) on an opposing end of the locking rail 4 allows for support by an edge of a support aperture 16 formed in the post 10 so locking rail 4 can be supported by the posts (8, 10). Further, the alignment rail 6 can be supported in similar fashion. Support apertures (12,14; 12′,14′ in first post 8) (16,18; 16′,18′ in second post 10) can be formed in opposing sides of each post as on post 8 or formed on adjacent sides as on post 10, for example, a corner post. Further, support apertures can be formed on any of the sides of a post (8, 10), without departing from the spirit of the invention. Although FIG. 3 illustrates adjacent support apertures (12, 12′) being formed at the same height, one skilled in the art will readily understand that the support apertures can be formed at any height, independent of any other support apertures present.

FIG. 4 is a top perspective view of the locking rail 4, showing the lateral offset of the locking aperture 26 with opposing edges (28, 30) and an alignment aperture 32 with opposing edges (34, 36).

FIG. 5 is a top perspective view of the alignment rail 6. Alignment rail 6 has an alignment aperture 40 which can be sized so as to slidably receive picket 2, but restrict lateral movement thereof. Although alignment aperture 40 is shown in the upper surface thereof, the alignment rail 6 can be tubular or inverted so that an alignment aperture 40 is additionally or alternatively along the bottom surface, however, the retaining slot 42 can then be formed in the opposite surface as is illustrated. Although shown as a U-channel rail, any shape of rail can be used. For example, a tube similar to the illustrated locking rail 4 can be used, with the alignment aperture 40 formed in the tube to create a rectangular bore through the tube or, if hollow, a set of adjacent, non-offset, alignment apertures can be formed in the upper and lower surface. Alignment aperture 40 need not have the same profile as alignment aperture 32, especially if the picket does not have a uniform profile.

Turning now to FIG. 6, one step of assembly of the interlocking fence system is shown. A picket 2 is disposed through the locking aperture 26 and the alignment aperture 32. Locking aperture 26 is laterally offset from alignment aperture 32, preferably at a length equal to the depth of the locking slot 22, shown more readily in FIG. 4. The profiles of the locking aperture 26 and/or alignment aperture 32 are sized to allow the disposition of the picket 2 at an offset angle. Thus, edge 30 of rectangular locking aperture 26, and edge 34 of the rectangular alignment aperture 32, can be spaced from opposing edge 28 and opposing edge 36, respectively, to allow sufficient play for the passage of the picket 2. The transverse profile of the picket 2 and the profiles of the apertures (26, 32) can be selected to enable the picket 2 to be inserted into the locking rail 4 at an angle with respect to an axis defined by the alignment apertures.

Picket 2 is inserted into the locking aperture of the locking rail 4 until edge 28, which forms the insertion tab, is adjacent locking slot 22. The picket 2 can then be pivoted into alignment with the axis of the alignment apertures, preferably vertically, until the locking slot 22 engages a desired edge 28 of the offset locking aperture 26. The edge 36 of alignment aperture 32 is spaced so as to contact picket 2, preferably when the picket is substantially perpendicular to the locking rail 4. Referring to the orientation shown, any proximal or distal movement is impeded by the opposing edges (31, 33 in FIG. 4) which can be spaced relatively close to the transverse profile of picket 2, whereas the distance between the other set of opposing edges (for example, 28, 30) can be spaced larger than the transverse profile of the picket 2 to allow for the passage of the picket 2 through the aperture (for example, 26). Edge 30 can also be spaced to allow locking slot 22 of the picket 2 to become unengaged from edge 28 of the locking aperture 26. The picket can be installed through the apertures (26, 32) in any order. Further, any number of pickets can be installed, with a respective locking aperture 26 and an alignment aperture 32 formed in the locking rail 4, and an alignment aperture 40 formed in the alignment rail 6.

FIG. 7 shows the picket 2 installed in the locking rail 4, which includes retaining slots (24, 24′) formed adjacent each end. Due to the spacing and geometry of the picket 2 and locking aperture 26, picket 2 is retained in the locking rail 4. In the orientation shown, clockwise movement between the picket 2 and the locking rail 4 would be impeded by the interaction of the outer surface of picket 2 and edge 36 of alignment aperture 32 as well as the interaction of the inner edge of the locking slot 22 and the edge 28 of the locking aperture 26. However, counterclockwise movement of the picket 2 relative to the locking rail 4 can cause the locking slot 22 to become disengaged from the edge 28 of the aperture 26 formed in the locking rail 4 (as shown in FIG. 6). To further retain the picket 2 within the locking rail, the invention provides an alignment rail 6. Alignment rail 6 includes an alignment aperture 40, shown here as a U-channel rail. The picket 2 can be inserted through alignment aperture 40, here by disposing alignment rail 6. The profile of alignment aperture 40 can be substantially similar to that of the transverse profile of the picket 2, preferably providing a gap therebetween to facilitate insertion of the picket 2 into the alignment aperture 40. Adjacent edges (44, 46) can be spaced relatively closer than the adjacent edges (34, 36) of the alignment aperture 32 in the locking rail 4 because the picket 2 can be inserted perpendicular to the alignment aperture 40.

FIG. 8 illustrates the picket 2, locking rail 4, and alignment rail 6 in 25 interlocked position, assuming the rails (4, 6) are fixed to the posts (8,10 in FIG. 1). The interaction of the outer surface of the picket 2 and edge 46 of the alignment aperture 40 in the alignment rail 6 can inhibit any counterclockwise movement, and thus create an interlocked picket 2, locking rail 4, and alignment rail 6 without the use of any fasteners or welding therebetween.

Although shown with the locking aperture 26 formed in the upper surface of the locking rail 4 and the locking rail 4 being the upper rail in the system, the invention is not so limited. A picket with at least one locking slot and any two rails including at least two alignment apertures and at least one locking aperture can be used to inhibit axial and lateral movement to create an interlocked fence system. For example, an upper rail can be made of rectangular tubing and provided with a locking aperture in a lower surface and an alignment aperture in the upper surface. Placing the locking apertures in the lower surface of the rails below eye level can help visually conceal the locking slot, which makes the fence aesthetically more attractive. Further, the lower rail can additionally or alternatively be made of rectangular tubing and provided with a locking aperture in either the upper surface or preferably the lower surface and an alignment aperture in the other of the upper and lower surfaces. Similarly, three rails one with a locking aperture and two with an alignment aperture can be used without departing from the spirit of the invention. It is the interaction of the offset locking aperture 26 and the locking slot 22 and the picket 2 and two edges (36, 46) of the alignment apertures (32, 40) in the embodiment shown that creates the interlock. Further, any number of locking rails 4, locking slots 22 in a picket 2, and/or alignment rails 6 can be utilized with each individual picket (e.g., a plurality of alignment rails can be added). Further a plurality of the rails can provide a combination of the locking and alignment functionalities, e.g. an alignment aperture in one surface and a locking aperture in the opposite surface.

FIGS. 9A-9B illustrate the mounting of the rails (4, 6) to posts (8A, 10A) without the use of fasteners or welding. Each post (8A, 10A) can have multiple support apertures to mount other sections fence, as is described above. Upright and spaced-apart posts are attached to grade G by any means known the art. In FIG. 9A, a locking rail 4 and an alignment rail 6 are interlocked with pickets 2, as is described above. The ends of the rails can then be disposed within a support aperture formed in each post. The end of the locking rail 4 with retaining slot 24 formed therein is disposed within the support aperture 12 formed in the post 8A. The locking rail 4 can then be displaced within the post 8A until 30 there is sufficient clearance between the opposite end of the locking rail and the post 10A, and the opposite end of the locking rail 4 can be moved laterally into alignment and inserted into the support aperture 16 formed in post 10A by moving the locking rail axially. The locking rail 4 can then be axially displaced toward post 10A until both retaining slots (24, 24′) are disposed into contact with an edge (38, 38′) of the respective support aperture (12, 16).

Similarly, the end of the alignment rail 6 with retaining slot 42 formed therein is disposed within the support aperture 14 formed in the post 8A. The alignment rail 6 can then be displaced within the post 8A until the opposite end of the alignment rail 6 can be inserted into the support aperture 18 formed in post 10A. The alignment rail 6 can then be displaced toward post 10A until both retaining slots (42, 42′) are disposed into contact with an edge (50, 50′) of the respective support aperture (14, 18). The fence can thus be used for temporary or permanent purposes. With a temporary use, a post can be moored to the grade by any means known in the art, for example, a removable, weighted pedestal. If hollow posts (8A, 10A) are utilized, as shown, a post can be filled with a hardenable filler, for example, cement, adjacent a support aperture to more permanently attach a rail (4, 6) to a post (8A, 10A).

The combination of the retaining slots (24,24′; 42,42′), support apertures (12, 14, 16, 18), and gravity thus retain the rails (4, 6) and interconnected pickets 2 to the posts (8A, 10A). Although four pickets are 20 shown, and number can be used without departing from the spirit of the invention. The retaining slots (24,24′; 42,42′) and support apertures (12, 14, 16, 18) can be designed to allow the insertion and displacement above, as is known to one of ordinary skill in the art.

Although FIGS. 9A-9B illustrate the pickets 2 installed before 25 installing the locking 4 and alignment rails 6 to the posts (8A, 10A), either rail (4, 6) can be installed to a post, of both posts (8A, 10A) independently of each other and/or the presence of a picket 2. Similarly, the locking rail 4 can be installed to the posts (8A, 10A), the pickets 2 installed in the locking rail 4, the alignment rail 6 installed to the pickets 2, and the alignment rail 6 installed to the posts (8A, 10A). Further, multiple posts, rails, and pickets can be used to form any desired length of fence comprising multiple sections of the interlocking fence section 1 shown in FIG. 1. For example, the fence section shown of FIGS. 9A-9B can be constructed by first installing the posts (8A, 10A) to the grade G, such as by recessing in a cement hole. The locking rail 4 can then attached to both left and right posts (8A, 10A). Preferably, the locking rail 4 has a retaining slot (24, 24′) formed adjacent both ends, preferably at an equal distance from each end, and a spacing between the retaining slots (24, 24′) corresponds to a spacing between support apertures (12, 16) formed in the first and second posts. The support aperture 12 in the first post 8A, which can be hollow or solid, preferably has a depth that is at least equal to the sum of the respective distances from the ends of the locking rail 4 to the respective retaining slots (24, 24′). To install the locking rail 4, a user can insert a first end of the locking rail 4 into the first support aperture 12 while the second end is positioned laterally to one side of the second post 10A, preferably adjacent the second support aperture 16, to provide clearance between the second end of the locking rail 4 and the second post 10A. A user can then laterally pivot the second end of the locking rail 4 into alignment with the second support aperture 16 in the second post 10A and move the locking rail 4 axially to position the first 24 and second 24′ retaining slots adjacent respective edges (38, 38′) of the first 12 and second 16 support apertures. Further, a user can move the locking rail 4 laterally, preferably downwardly, to engage the respective edges (38, 38′) of the first and second support apertures (12, 16) in the first and second retaining slots (24, 24′). Next, a picket 2 or plurality of pickets, can be installed in the locking rail 4, as described above.

Finally, the pickets 2 can be installed to the alignment rail 6 and the alignment rail attached to the posts (8A, 10A). For example, the alignment rail 6 can be disposed adjacent to the posts (8A, 10A) and the lower ends of the pickets 2. The alignment rail can by disposed toward the ends of each picket 2 and the ends of a picket 2 can then be disposed laterally, which can be facilitated by the gap formed between each picket 2 and locking rail 4 apertures, to insert each picket 2 through a respective alignment aperture 40 (or apertures) in the alignment rail 6. After each picket 2 is installed, the alignment rail 6 can be attached to both left and right posts (8A, 10A). Preferably, the alignment rail 6 has a retaining slot (42, 42′) formed adjacent both ends, preferably at an equal distance from each end, and a spacing between the retaining slots (42, 42′) corresponds to a spacing between support apertures (14, 18) formed in the first and second posts. The support aperture 14 in the first post 8A, which can be hollow or solid, preferably has a depth that is at least equal to the sum of the respective distances from the ends of the alignment rail 6 to the respective retaining slots (42, 42′). To install the alignment rail 6, a user can insert a first end of the alignment rail 6 into the first support aperture 14 while the second end is positioned laterally to one side of the second post 10A, preferably adjacent the second support aperture 18, to provide clearance between the second end of the alignment rail 6 and the second post 10A. Then a user can laterally pivot the second end of the alignment rail 6 into alignment with the second support aperture 18 in the second post 10A and move the alignment rail 6 axially to position the first 42 and second 42′ retaining slots adjacent respective edges (50, 50′) of the first 14 and second 18 support apertures. Further, a user can move the alignment rail 6 laterally, preferably downwardly, to engage the respective edges (50, 50′) of the first and second support apertures (14, 18) in the first and second retaining slots (42, 42′). Alternatively, the pickets 2, alignment rail 6, and locking rail 4 can be interlocked before insertion of the ends of each rail (4, 6) to each post (8A, 10A) in the manner described above.

As each post (8, 10) can have multiple support apertures (12′, 14′; 16′, 18′ in FIG. 1), further sections of fence can be added, for example by adding a third post (not shown).

Referring to FIGS. 1-9B, the fence system can include a stop (not shown) made of any material, for example, elastomer, that is inserted in the locking aperture 26 on a side of the locking rail 4 opposite the locking slot 22 of an installed picket 2 to inhibit release of the edge 28 of the locking aperture 26 from the locking slot 22. A stop can be inserted into a support aperture (12, 14, 16, 18) on a side of a installed rail (4, 6) opposite a respective retaining slot (24, 42, 24′, 42′) to inhibit release of the edges (38, 50, 38′, 50′) of the support apertures (12, 14, 16, 18) from the retaining slots (24, 42, 24′, 42′). Alternatively or additionally, the fence system can include an end stop (not shown) inserted in at least one of the posts (8, 10) adjacent the end of the respective rail (4, 6) to inhibit axial movement of the rail. In one embodiment, the end stop can be a successive alignment rail (not shown) engaged in a successive support aperture (e.g., 12′, 14′, 16′, 18′) opposite a respective support aperture (12, 14, 16, 18). In one embodiment, the posts (8, 10) are tubular and the end stop can be formed by filling the posts (8, 10) adjacent a support aperture (12, 14, 16, 18) with a hardenable filler such as cement, for example.

The disclosed interlocking fence system can allow simple manufacturing, for example, by sawing and/or hole punching. No damage to the protective coating during assembly as there are no fasters, for example, screws, or welding to damage the rust protection, which can necessitate repair in the field. No tools are required for assembly. The interlocking panels formed by rails and pickets can follow the ground contour easily owing to the non-rigid manner of the interlock and are not limited to a stair step mounting as is with typical prefabricated welded panels. The interlocking fence system allows visual symmetry as both sides of the fence look the same. The size of each interlocked panel and/or the entire interlocking fence system can be scaled up or down for residential, commercial and industrial applications.

Turning now to FIGS. 10-12, a second embodiment of pickets 2A is illustrated. The picket 2A, which can be solid, is representative of the kind typically used in a privacy fence, as is known to those skilled in the art. A locking slot 22 and locking can be formed in the picket 2A, as above. Two parallel rows of spaced pickets (2A, 2B) can be mounted in an offset pattern as seen in FIG. 12 using a locking rail 4′ and an alignment rail 6′ with similarly laterally offset locking apertures 26′ and alignment apertures 32′. The pickets in each row are thus offset so that the pickets in one row are positioned opposite the spaces between the pickets in the other row so that there is no line of sight between the pickets and the inside and outside view of the fence panel does not differ.

Another embodiment shown in FIGS. 13-18 employs pickets with a plurality of locking slots including a locking slot cooperating with respective locking and alignment apertures in each rail. This arrangement has the advantage of improved structural integrity, for example, in longer spans the plural locking slots can inhibit rail sag by supporting a portion of the weight of each picket on each rail.

FIG. 13 is a perspective view of a picket 102 with an upper locking slot 104 and a lower locking slot 106, according to an embodiment of the invention. Damping inserts 108, 110 in the form of circular rubber or plastic tubes or short hose sections can be friction fit in respective upper ends of the picket 102, which in an embodiment are square or rectangular tubes. The inserts 108, 110 can have a compressibility and an outside diameter matching the internal dimensions of the tubular picket 102 so that the inserts 108, 110 can be easily inserted into the ends of the picket 102 and pushed inwardly to hide them from view, but are sufficiently tight to be retained in place during the assembly process. In one embodiment, the slots 104, 106 can optionally be disposed on the same side of the picket 102, or on opposite sides not shown).

FIG. 14 is a cross-sectional view of the double-locking picket 102 of FIG. 13 used in an interlocking fence system 100 according to an embodiment of the invention. The picket 102 is shown engaged with upper rail 112 and lower rail 114. The upper rail 112 has a locking aperture 116 formed in a lower surface thereof. Edge 118 of the locking aperture 116 in the upper rail 112 serves as a tab to restrict axial movement by insertion into the locking slot 104 on the picket 102.

The picket 102 is also disposed through alignment aperture 120 formed in the upper surface of the upper rail 102. Opposite edge 122 of alignment aperture 120 is laterally spaced from the locking edge 118 less than the transverse dimension of the picket 102 to engage the side of the picket 102 opposite the slot 104 and restrict the lateral movement of the picket 102 beyond vertical. The opposite edge 124 of the locking aperture 116 is spaced away from the picket 102 a distance that is slightly greater than the depth of the slot 104 to facilitate assembly as discussed in more detail below. Also, the edge 126 of the alignment aperture 120 is similarly spaced from the vertical picket 102 to facilitate assembly.

The lower rail 114 similarly has a locking aperture 128 formed in a lower surface thereof. Edge 130 of the locking aperture 128 in the lower rail 114 serves as a tab to restrict axial movement by insertion into the locking slot 106 on the picket 102. In this manner support of the weight of the picket 102 is shared by both of the upper rail 112 and the lower rail 114.

The picket 102 is also disposed through alignment aperture 132 formed in the upper surface of the lower rail 114. Opposite edge 134 of alignment aperture 132 is laterally spaced from the locking edge 130 less than the transverse dimension of the picket 102 to engage the side of the picket 102 opposite the slot 106 and restrict the lateral movement of the picket 102 beyond vertical. The opposite edge 136 of the locking aperture 128 is spaced away from the picket 102 a distance that is slightly greater than the depth of the slot 106 to facilitate assembly as discussed in more detail below. Also, the edge 138 of the alignment aperture 132 is similarly spaced from the vertical picket 102 to facilitate assembly.

In an embodiment, the tab 118 and the lateral offset between the alignment aperture 120/locking aperture 116 at the upper rail 112 can be deeper/longer than the corresponding tab 130 and lateral offset of the apertures 132, 128 at the lower rail 114, e.g. in an embodiment the tab 118 is about twice as long as the tab 130, to facilitate assembly as discussed below. The greater offset in the upper rail requires a greater angle of the picket for insertion, and thus, when the picket is inserted in the lower rail at a lower angle, the picket will not disengage or come loose from the upper rail.

The resilient inserts 108 and 110 are compressed by the respective locking edges 118 and 130 to provide dampening and inhibit rattling of the fence system 100 when subjected to vibration, wind etc.

In all other respects, the fence assembly 100 of FIG. 14 is similar to that shown in FIGS. 1-9B above, i.e. the same post 8, support apertures 12,12′, retaining slots 24, and tabs 38 can be used to secure the rails 112, 114 to the posts 8, as previously described.

FIG. 15 is an assembly schematic wherein the double locking picket 102 of FIG. 13 and additional locking pickets 102A, 102B etc. are shown with the upper ends inserted into the upper rail 112, according to an embodiment of the invention. The manner of inserting the pickets 102, 102A, 102B etc. into the upper rail 112 is similar to the method described above in reference to FIG. 6, i.e. a picket is angled for insertion through the apertures 116, 120 and advanced until the locking slot 104 is aligned with the locking edge 118, and then the picket is rotated to engage the edge 118 in the slot 104. The procedure is repeated until each of the desired pickets is engaged in the upper rail 112.

FIG. 16 is a schematic view of the double-locking pickets of FIGS. 13-15 during assembly wherein, following engagement of each of the pickets in the upper locking rail as shown in FIG. 15, the lower ends of the pickets 102, 102A, 102B, etc. are partially inserted into a respective one of the upper apertures 132, 132A, 132B, etc. of the lower rail 114.

FIG. 17 is an assembly schematic view following FIG. 16 wherein the lower rail 114 is moved longitudinally with respect to the upper rail 112 to align the lower ends of the pickets 102, 102A, 102B, etc. and slide them into the respective locking apertures 128, 128A, 128B, etc. by moving the lower rail 114 up with respect to the upper rail 112, while at the same time maintaining the upper ends of the pickets 102, 102A, 102B, etc. in engagement with the upper rail 112.

FIG. 18 is an assembly schematic following FIG. 17 wherein the tabs 130, 130A, 130B, etc. are engaged in the respective slots 106, 106A, 106B, etc. and then the lower rail 114 is moved longitudinally with respect to the upper rail 112 to pivot the pickets 102, 102A, 102B, etc. so that each lower locking slot 106, 106A, 106B, etc. is locked on the respective tabs 130, 130A, 130B, etc. and the pickets 102, 102A, 102B, etc. are aligned vertically in the alignment apertures 120, 120A, 120B, etc. and 132, 132A, 132B, etc. in the upper and lower rails 112, 114, to the position in the final assembly configuration as shown FIG. 14.

FIGS. 19 and 20 illustrate an alternative embodiment of the interlocking fence system according to the invention wherein a transverse support pin 200 is used adjacent the lower rail 6. In this embodiment the pin 200 is pushed through a bore in the picket 2 and extends outwardly from the sides of the picket 2 as best seen in FIG. 20, so the ends of the pin 200 can rest on the top of the rail 6 to carry all or at least a portion of the weight of the picket 2 to help avoid sagging of the upper rail 4. Preferably, the ends of the pin 200 are flush with the outer surfaces of the rail. The lower pin 202 seen in FIG. 19 is similar to the upper pin 200, and can be provided as an alternative or in addition to the pin 200. The lower pin 202 has its opposite ends supported in respective bores formed through the side walls of the rail 6.

Although illustrated with square or rectangular tubing and apertures, other profiles can be used without departing from the spirit of the invention, including, for example, circular or non-circular, ovate, polygonal, cylindrical, tapered, regular, irregular or the like, or various combinations thereof, including different profiles on the same or different pickets, rails, posts, and/or apertures. A picket, post, or rail can be any material, including, but not limited to, metal, wood, plastic, or the like, and various combinations and composites thereof. Each picket, rail, and/or post can be any length desired.

While the invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of the invention. 

1. A method of assembling an interlocking fence system comprising the following steps: (a) providing an interlocking fence system comprising: upper and lower rails each including a like plurality of spaced apart alignment apertures, wherein at least one of the upper and lower rails is tubular wherein the respective alignment apertures are formed in one of an upper and a lower surface thereof and a like plurality of spaced apart locking apertures is formed in the other one of the upper and lower surfaces, and a plurality of pickets with a transverse profile and a locking slot extending inwardly from a side surface thereof for receiving a tab defined by an edge of the locking aperture; (b) inserting a respective one of the pickets through each of the locking and alignment apertures in the tubular rail and a first one of the alignment apertures in the tubular rail at an offset angle to position the locking slot adjacent the tab; (c) pivoting the pickets from the offset angle to an alignment angle to engage the tab into the locking slot, and (d) inserting each of the pickets through a second one of the alignment apertures and coaxially aligning the alignment apertures.
 2. The method of claim 1 further comprising: installing first and second upright, laterally spaced posts in a grade; securing opposite ends of the at least one tubular rail to the posts; and securing opposite ends of the other of the upper and lower rails to the posts, wherein the upper and lower rails are vertically spaced from each other.
 3. The method of claim 2 wherein the tubular rail is secured to the posts before the other of the upper and lower rails.
 4. The method of claim 3 wherein the steps of securing the opposite ends of the rails comprise: disposing one of the ends of the respective rail into a support aperture in one of the posts to position a retaining slot formed in the respective rail adjacent an edge of the support aperture; and moving the respective rail transversely to engage the edge in the retaining slot.
 5. The method of claim 4 wherein the steps of securing the opposite ends of the rails comprise the steps of: (1) inserting a first end of the respective rail into a first support aperture in the first post while a second end is positioned laterally to one side of the second post adjacent a second support aperture to provide clearance between the second end of the respective rail and the second post; (2) laterally pivoting the second end of the respective rail into alignment with the second support aperture in the second post; (3) moving the respective rail axially to position a first and a second retaining slot adjacent a respective edge of the first and second support apertures; and (4) moving the respective rail laterally to engage the respective edges of the first and second support apertures in the first and second retaining slots.
 6. The method of claim 5 further comprising: inserting at least one stop into each of the first and second support apertures on a side of the respective rail opposite the respective first and second retaining slots to inhibit release of the edges of the support apertures from the retaining slots.
 7. The method of claim 6 further comprising: inserting an end stop in at least one of the posts adjacent the end of the respective locking and alignment rails to inhibit axial movement of the respective locking and alignment rails.
 8. The method of claim 4 further comprising: providing tubular posts; and filling the posts adjacent the support aperture with a hardenable filler.
 9. An interlocking fence system comprising: first and second spaced-apart upright posts attached to a grade; upper and lower rails extending between the first and second posts, wherein at least one of the upper and lower rails is tubular; a picket with a transverse profile and a locking slot extending inwardly from a side surface thereof, wherein the picket passes through the rails at a locking aperture and is then pivoted into alignment with an axis of a plurality of spaced apart, coaxial alignment apertures; the plurality of alignment apertures in the rails comprising-at least one alignment aperture in each of the upper and lower rails, wherein the alignment aperture in the at least one tubular rail is in one of an upper or a lower surface thereof and the locking aperture is in the other one of the upper or lower surfaces, wherein the alignment apertures have a profile matching the transverse profile of the picket and are in upright alignment with respect to an axis of the picket to restrict lateral movement of the picket; and the locking aperture formed has a profile matching the transverse profile of the picket to receive the picket at an angle offset from an axis of the alignment apertures for assembly, wherein the locking aperture is offset laterally with respect to the axis of the picket, wherein the lateral offset of the locking aperture defines a tab inserted into the locking slot with the picket aligned by the alignment apertures.
 10. The interlocking fence system of claim 9 wherein the locking aperture is formed in the upper surface of the tubular rail.
 11. The interlocking fence system of claim 9 wherein the upper rail is tubular.
 12. The interlocking fence system of claim 9 wherein both of the upper and lower rails are tubular.
 13. The interlocking fence system of claim 9 further comprising a plurality of said pickets, each with a corresponding locking aperture and plurality of alignment apertures formed in the rails receiving the picket.
 14. The interlocking fence system of claim 9 wherein a depth of the locking slot is at least equal to the lateral offset of the locking aperture.
 15. The interlocking fence system of claim 9 further comprising inwardly extending retaining slots formed in a side surface adjacent an end of the upper and lower rails to receive a respective edge of a support aperture in a respective post.
 16. A method of assembling an interlocking fence system comprising the following steps: (a) providing an interlocking fence system comprising: a plurality of vertically spaced tubular rails including at least an upper rail and a lower rail, each rail including a like plurality of spaced apart alignment apertures formed in an upper surface of the rails, and a like plurality of locking apertures formed in a lower surface of the rails, wherein each of the alignment apertures is laterally offset from a respective locking aperture to define a locking tab at an edge of the locking aperture, wherein a picket retention corridor is defined by each set of corresponding alignment and locking apertures among the plurality of rails, and a plurality of pickets having locking slots extending inwardly from a side surface thereof for receiving the tabs from the locking apertures in a profile for retention in the picket retention corridor; (b) inserting one of the plurality of the pickets through each of the corresponding locking and alignment apertures of the upper rail in a respective picket retention corridor at a first offset angle to position the corresponding locking slot adjacent the tab; (c) pivoting the pickets inserted in step (b) from the first offset angle toward an alignment angle to engage the tab into the corresponding locking slot and lock the picket s in the upper rail, and (d) inserting one of the locked pickets from step (c) through each of the corresponding locking and alignment apertures of the lower rail in a respective picket retention corridor at a second offset angle to position the corresponding locking slot adjacent the tab in the lower rail; and (e) pivoting the pickets inserted in step (d) from the second offset angle toward an alignment angle to engage the tab into the corresponding locking slot and lock the pickets in the lower rail and to coaxially align the alignment apertures in each picket retention corridor.
 17. The method of claim 16 further comprising: installing first and second upright, laterally spaced posts in a grade; and securing opposite ends of the upper and lower rails to the posts.
 18. The method of claim 17 wherein the step of securing the opposite ends of the rails comprises: disposing one of the ends of the respective rail into a support aperture in one of the posts to position a retaining slot formed in the respective rail adjacent an edge of the support aperture; and moving the respective rail transversely to engage the edge in the retaining slot.
 19. The method of claim 17 wherein the step of securing the opposite ends of the rails comprises the steps of: (1) inserting a first end of the respective rail into a first support aperture in the first post while a second end is positioned laterally to one side of the second post adjacent a second support aperture to provide clearance between the second end of the respective rail and the second post; (2) laterally pivoting the second end of the respective rail into alignment with the second support aperture in the second post; (3) moving the respective rail axially to position a first and a second retaining slot adjacent a respective edge of the first and second support apertures; and (4) moving the respective rail laterally to engage the respective edges of the first and second support apertures in the first and second retaining slots.
 20. The method of claim 17 further comprising: providing tubular posts; and filling the posts adjacent the support aperture with a hardenable filler.
 21. An interlocking fence system comprising: first and second spaced-apart upright posts attached to a grade; upper and lower tubular rails extending between the first and second posts; a picket with a transverse profile and upper and lower locking slots extending inwardly from a side surface thereof, wherein the picket passes through each of the rails at a respective locking aperture and is then pivoted into alignment with an axis of respective alignment apertures in each of the upper and lower rails, wherein the locking apertures are laterally offset from the respective alignment apertures to define a locking tab received in the locking slot of the picket.
 22. The interlocking fence system of claim 21 wherein the alignment apertures are formed in upper surfaces of the rails and the locking apertures are formed in lower surfaces of the rails.
 23. The interlocking fence system of claim 21 further comprising a plurality of said pickets.
 24. The interlocking fence system of claim 21 wherein the lateral offset of the locking apertures from the alignment apertures in the upper rail is greater than the lateral offset of the locking apertures from the alignment apertures in the lower rail.
 25. The interlocking fence system of claim 24 wherein the lateral offset of the locking apertures from the alignment apertures in the upper rail is about 1.5 to 2.5 times the lateral offset of the locking apertures from the alignment apertures in the lower rail. 